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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 2, Problem 42

Solve each quadratic inequality. Give the solution set in interval notation. x2-7x+10>0

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Start by rewriting the inequality: \(x^{2} - 7x + 10 > 0\).
Factor the quadratic expression on the left side: \(x^{2} - 7x + 10 = (x - 5)(x - 2)\).
Identify the critical points by setting each factor equal to zero: \(x - 5 = 0\) gives \(x = 5\), and \(x - 2 = 0\) gives \(x = 2\).
Use the critical points to divide the number line into intervals: \((-\infty, 2)\), \((2, 5)\), and \((5, \infty)\). Test a value from each interval in the inequality \((x - 5)(x - 2) > 0\) to determine where the product is positive.
Based on the test results, write the solution set in interval notation, including only the intervals where the inequality holds true.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Quadratic Inequalities

A quadratic inequality involves a quadratic expression set greater than or less than zero (or another value). Solving it means finding all x-values that make the inequality true, often by analyzing the sign of the quadratic expression over different intervals.
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Factoring Quadratic Expressions

Factoring rewrites a quadratic expression as a product of two binomials. For example, x² - 7x + 10 factors to (x - 5)(x - 2). Factoring helps identify the roots, which are critical points dividing the number line into intervals for testing the inequality.
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Interval Notation and Sign Analysis

Interval notation expresses solution sets as ranges of values. After finding roots, the number line is split into intervals. Testing a point from each interval in the inequality determines where the expression is positive or negative, guiding the correct solution intervals.
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